An alternative and very general approach to proving \(L^p\)  bounds on both wave and Schrödinger evolutions was found by Yajima [1]}, [2]} who proved \(L^p\)  boundedness of the
wave operators, with the limit being taken in the strong \(L^2\) -sense,
\(W = \lim _{t\rightarrow \infty } e^{-itH} e^{-it\Delta }\) 
